eulgeneral

Hello,

I plan to build a F-86 Sabre fro a Ramtec ducted fan with an OS 91. I choose this plane because I'm a beginner in jet mlodels and this aicraft have a good inlet surface.

My first problem is that I haven(t got any documentation or plan so I'm asking you to have a 3 views plan with fuse section if possible?

My second question is about the ratio between inlet, fan and outlet surface. What is the best value for those parameters?

Thanks

Yannick
France

HalH

My Feedback: (12)

You would save yourself a great deal of time and money if you bought an already proven model.Three very good ones are made by BVM jets,Jet Hangar Hobbies and Trim.

eulgeneral

Thanks,

but my main problem is the money: I don't have enough to buy one of these kits. I know that it would be easier to buy one but I'm not ready to spend 800 - 1200 dollars for a "simple" kit. I have a lot of time to build but not many money, that's really a dilemma! I'm not a beginner in model conception but I don't have any experience in ducted fan. Perhaps do you know if there is good plans on the market?

Thanks

Yannick

Stratotanker

My Feedback: (3)

Have you done a search in the forums yet?, this question has been asked alot. A starting point for the inlet duct should be around 90% of the swept area of the fan, it should have nice rounded inlet lips so the airflow stays clean. The exhaust duct has some variance on its size depending on what you want to do with your plane. For less thrust and more speed the outlet should be somewhere around 3.25" and 4" for more thrust and less speed. These are just starting points of what I learned when I was thinking about doing a smaller F-86. There are a more variables to consider than I know anything about! Any thing you do inside the duct be very careful that the changes in shape are not sharp or have any drastic changes in shape, any turbulence you create in the inlet is costing you thrust. Make sure that the overall weight of the plane is considered as ducted fans are very sensitive to air density the hotter it is the less thrust you are developing(learned that one the hard way!). You are in for a long road of making and testing duct design to get it right, not that it can't be done though! Maybe a good thing for you to consider is to get the propulsion package that you want and then see if you can buy the inlet and exhaust ducts from trim(if using the Ramtec) and then design your plane around that. Hope this helps without discouraging you too much. Good luck!

Chris

eulgeneral

Thank you Chris. It will be very helpfull to me. I have a lot of courage and tests don't afraid me!

Yannick